So I have had this overheating problem on my caddy appear after letting it sit for over a year.
I fire it up drive down the road all is cool. Get on the hiway and WOT it to 90 and it startd dinging at me talking about overheating and coolant low.
I pull over call the tow truck get it home.
I started looking for leaks or signs of leaks. None. About 8 months before garaging it I replaced the water pump. I stopped driving it because I bought a jeep to drive instead (it's easier to haul the fishing gear in it).
Anyways I drained and filled with water and cleaner. said to drive for 3 hours. Well I drive it to work 1 time a week just to get it flowing around in there. Yesterday it overheated after a brief drive to the store. It boiled out of the reservoir.
So last night i removed the cap and thermostat. I boiled some water up to 185 and it started to open. So i know it work, but it may also be intermittently sticking. Who knows. So I will be replacing that as it's a cheap part.
I got my buddy's snap-on cooling system tester and tested the cap. I wetted the seals and put it to the test. Pumped it to 15psi and it started letting air out. I then watched it drop to 10 psi quickly then slowly taper off at 7psi.
I put it under a pan of water to see if the pump was leaking ot the cap. It was the cap leaking bubbles.
I also blew compressed air through the purge line coming out of the water pump housing to clear that as well. Do not know if it was clogged or not but it can't hurt.
I sure hope this cap is my only issue because someone I know through someone else is looking at buying the caddy for $5k and I would hate to sell it to someone I have to deal with if it's a blown headgasket. If it's the HG I am takign is straight to the dealer and trading it in before the engine warms up.
I guess I am asking for reassurance that you all think it is the cap causing my issues here before I get too stressed over this ordeal.